Astronomy Chapter 11 Test Questions – Flashcards

According to modern science, approximately how old is the Sun? A.10,000 years B.4 ½ billion years C.400 million years. D.25 million years

The Sun will exhaust its nuclear fuel in about ______. A.5 billion years B.50 billion years C.5000 AD D.5 million years

Which of the following correctly describes how the process of gravitational contraction can make a star hot? A.Heat is generated when gravity contracts, because gravity is an inverse square law force. B.Gravitational contraction involves nuclear fusion, which generates a lot of heat. C.Gravitational contraction involves the generation of heat by chemical reactions, much like the burning of coal. D.When a star contracts in size, gravitational potential energy is converted to thermal energy.

The source of energy that keeps the Sun shining today is _________. A.gravitational contraction B.nuclear fission C.nuclear fusion D.chemical reactions

What two physical processes balance each other to create the condition known as gravitational equilibrium in stars? A.gravitational force and surface tension B.gravitational force and outward pressure C.the strong force and the weak force D.the strong force and the electromagnetic force

Energy balance in the Sun refers to a balance between _________. A.the mass that the Sun loses each second and the amount of mass converted into energy each second B.the rate at which fusion generates energy in the Sun's core and the rate at which the Sun's surface radiates energy into space C.the force of gravity pulling inward and the force due to pressure pushing outward D.the amount of energy the Sun radiates into space and the amount of energy that reaches Earth

When we say that the Sun is a ball of plasma, we mean that _________. A. the Sun is made of material that acts like a liquid acts on Earth B.the Sun is made of atoms and molecules C.the Sun is roughly the same color as blood D.the Sun consists of gas in which many or most of the atoms are ionized (missing electrons)

What is the Sun made of (by mass)? A.70% hydrogen, 28% helium, 2% other elements B.100% hydrogen and helium C.50% hydrogen, 25% helium, 25% other elements D.90% dark matter, 10% ordinary matter

From center outward, which of the following lists the "layers" of the Sun in the correct order? A.Core, radiation zone, convection zone, photosphere, chromosphere, corona B.Core, corona, radiation zone, convection zone, photosphere, chromosphere C.Core, convection zone, radiation zone, corona, chromosphere, photosphere D.Core, radiation zone, convection zone, corona, chromosphere, photosphere

What are the appropriate units for the Sun's luminosity?

The Sun's surface, as we see it with our eyes, is called the _________.

The Sun's average surface (photosphere) temperature is about ______. A.37,000 K B.1,000 K C.1,000,000 K D.5,800 K

What is the solar wind? A.the strong wind that blows sunspots around on the surface of the Sun B.a stream of charged particles flowing outward from the surface of the Sun C.the uppermost layer of the Sun, lying just above the corona D.the wind that causes huge arcs of gas to rise above the Sun's surface

The proton-proton chain is _________. A.the specific set of nuclear reactions through which the Sun fuses hydrogen into helium B.the linkage of numerous protons into long chains C.an alternative way of generating energy that is different from the fusion of hydrogen into helium D.another name for the force that holds protons together in atomic nuclei

The overall result of the proton-proton chain is: A.4 H becomes 1 He + energy B.p + p becomes 2H + energy C.6 H becomes 1 He + energy D.Individual protons are joined into long chains of protons.

Why are neutrinos so difficult to detect? A.No one knows: this is the essence of the "solar neutrino problem." B.They are extremely rare. C.They have no mass. D.They have a tendency to pass through just about any material without any interactions.

The light radiated from the Sun's surface reaches Earth in about 8 minutes, but the energy of that light was released by fusion in the solar core about _________. A.three days ago B.a few hundred thousand years ago C.one thousand years ago D.one hundred years ago

What happens to energy in the Sun's convection zone? A.Energy is transported outward by the rising of hot plasma and sinking of cooler plasma. B.Energy is produced in the convection zone by thermal radiation. C.Energy slowly leaks outward through the radiative diffusion of photons that repeatedly bounce off ions and electrons. D.Energy is produced in the convection zone by nuclear fusion.

What do sunspots, solar prominences, and solar flares all have in common? A.They all occur only in the Sun's photosphere. B.They all have about the same temperature. C.They are all shaped by the solar wind. D.They are all strongly influenced by magnetic fields on the Sun.

Which of the following is not a characteristic of the 11-year sunspot cycle? A.The Sun's entire magnetic field flip-flops with each cycle, so that the overall magnetic cycle averages 22 years. B.The number of sunspots on the Sun at any one time gradually rises and falls, with an average of 11 years between the times when sunspots are most numerous. C.The likelihood of seeing solar prominences or solar flares is higher when sunspots are more common and lower when they are less common. D.The sunspot cycle is very steady, so that each 11-year cycle is nearly identical to every other 11-year cycle.

How is the sunspot cycle directly relevant to us here on Earth? A.The brightening and darkening of the Sun that occurs during the sunspot cycle affects plant photosynthesis here on Earth. B.Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment. C.The sunspot cycle is the cause of global warming. D.The Sun's magnetic field, which plays a major role in the sunspot cycle, affects compass needles that we use on Earth. E.The sunspot cycle strongly influences Earth's weather.

In the late 1800s, Kelvin and Helmholtz suggested that the Sun stayed hot due to gravitational contraction. What was the major drawback to this idea? A.It predicted that the Sun would shrink noticeably as we watched it, but the Sun appears to be stable in size. B.It predicted that the Sun could shine for about 25 million years, but geologists had already found that Earth is much older than this. C.It is physically impossible to generate heat simply by making a star shrink in size. D.It predicted that Earth would also shrink in size with time, which would make it impossible to have stable geology on our planet.

When is/was gravitational contraction an important energy generation mechanism for the Sun? A.It has played a role throughout the Sun's history, but it was most important right after nuclear fusion began in the Sun's core. B.It is important during periods when the Sun is going from solar maximum to solar minimum. C.It was important when the Sun was forming from a shrinking interstellar cloud of gas. D.It is the primary energy generation mechanism in the Sun today.

What do we mean when we say that the Sun is in gravitational equilibrium? A.The Sun maintains a steady temperature. B.The Sun always has the same amount of mass, creating the same gravitational force. C.The hydrogen gas in the Sun is balanced so that it never rises upward or falls downward. D.There is a balance within the Sun between the outward push of pressure and the inward pull of gravity.

Which of the following is the best answer to the question, "Why does the Sun shine?" A.The Sun initially began generating energy through nuclear fusion as it formed, but today it generates energy primarily through the sunspot cycle. B.As the Sun was forming, nuclear fusion reactions in the shrinking clouds of gas slowly became stronger and stronger, until the Sun reached its current luminosity. C.The Sun initially began making energy through chemical reactions. These heated the interior enough to allow gravitational contraction and nuclear fusion to occur. D.As the Sun was forming, gravitational contraction increased the Sun's temperature until the core become hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine.

How does the Sun's mass compare to Earth's mass? A.The Sun's mass is about 300 times the mass of the Earth. B.The Sun's mass is about 30 times the mass of the Earth. C.Both have approximately the same mass. D.The Sun's mass is about 300,000 times the mass of the Earth.

Which of the following best describes why the Sun emits most of its energy in the form of visible light? A.The Sun's gas is on fire like flames from wood or coal, and these flames emit visible light. B.Nuclear fusion in the Sun's core produces visible light photons. C.The visible light comes from energy level transitions as electrons in the Sun's hydrogen atoms jump between level 1 and level 2. D.Like all objects, the Sun emits thermal radiation with a spectrum that depends on its temperature, and the Sun's surface temperature is just right for emitting mostly visible light.

Which of the following correctly compares the Sun's energy generation process to the energy generation process in human-built nuclear power plants? A.The Sun generates energy by fusing small nuclei into larger ones, while our power plants generate energy by the fission (splitting) of large nuclei. B.The Sun generates energy through nuclear reactions while nuclear power plants generate energy through chemical reactions. C.Both processes involve nuclear fusion, but the Sun fuses hydrogen while nuclear power plants fuse uranium. D.The Sun generates energy through fission while nuclear power plants generate energy through fusion.

Every second, the Sun converts about 600 million tons of hydrogen into 596 million tons of helium. The remaining 4 million tons of mass is __________. A.ejected into space by solar flares B.ejected into space in a solar wind C.reabsorbed as molecular hydrogen D.converted to an amount of energy equal to 4 million tons times the speed of light squared

Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together? A.Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold. B.Nuclei are attracted to each other by the electromagnetic force, but this force is only strong enough to make nuclei stick when they are very close together. C.Nuclei have to be very hot in order to fuse, and the only way to get them hot is to bring them close together. D.Fusion can proceed only by the proton-proton chain, and therefore requires that protons come close enough together to be linked up into a chain.

If the Sun's core suddenly shrank a little bit, what would happen in the Sun? A.The core would cool off and continue to shrink as its density increased. B.The density of the core would decrease, causing the core to cool off and expand. C.The core would heat up, fusion rates would increase, the core would re-expand. D.The core would heat up, causing it to radiate so much energy that it would shrink even more.

Why does the Sun emit neutrinos? A.The Sun was born with a supply of neutrinos that it gradually emits into space. B.Convection releases neutrinos, which random walk through the radiation zone. C.Fusion in the Sun's core creates neutrinos. D.Solar flares create neutrinos with magnetic fields. E.The Sun does not emit neutrinos.

If the Sun suddenly stopped emitting neutrinos, what might we infer (after checking that our neutrino detectors were still operational)? A.The Sun has exhausted its supply of neutrinos. B.Fission reactions in the Sun have ceased. C.Fusion reactions in the Sun ceased a few hundred thousand years ago. D.Fusion reactions in the Sun have ceased within the past few minutes.

How can we best observe the Sun's chromosphere and corona? A.The chromosphere and corona are both best studied with visible light. B.The chromosphere and corona are both best studied with radio telescopes. C.The chromosphere is best observed with infrared telescopes and the corona is best observed with ultraviolet telescopes. D.The chromosphere is best observed with ultraviolet telescopes and the corona is best observed with X-ray telescopes.

The intricate patterns visible in an X-ray image of the Sun generally show __________. A.structure within sunspots B.a bubbling pattern on the photosphere C.helioseismological fluctuations D.extremely hot plasma flowing along magnetic field lines

How can we measure the strength of magnetic fields on the Sun? A.By observing the sizes of sunspots: Bigger sunspots mean a stronger field B.By looking for the splitting of spectral lines in the Sun's spectrum C.Only by using sophisticated computer models, because there are no observational ways of measuring magnetic field strength D.By observing auroras here on Earth

Satellites in low-Earth orbits are more likely to crash to Earth when the sunspot cycle is near solar maximum because __________. A.they are more likely to have their electronics "fried" by a solar flare during solar maximum B.it is too dangerous to send the Space Shuttle to service satellites during solar maximum C.Earth's upper atmosphere tends to expand during solar maximum, exerting drag on satellites in low orbits D.of increased magnetic interference

Which of the following choices is not a way by which we can study the inside of the Sun? A.We can make a computer model of the Sun's interior that allow us to predict the observable properties of the Sun. B.We can study solar neutrinos. C.We can send a space probe into the Sun's photosphere. D.We can probe the interior of the Sun by studying the vibrations in its photosphere.